Core grinder



Jan. 21, 1947.

J. A. ROSMAIT 2,414,560

CORE GRINDER Filed Feb. 17, 1945 s Sheets-Sheet 1 IN VEN TOR.

Miwa/ A T T'OfFA/E Y5 Jan. 21, 1-947. J. A. ROSMAJT 2,414,560

CORE GRINDER Filed Feb. 17, 1945 3 Sheets-Sheet 2 IN V EN T OR.

Mat/5 A TTORA/EIYS.

Jan. 21, 1947. J. A. ROSMYAIT coma (GRINDER Filed Feb. 17, 1945 3Sheets-Sheet 3 INVENTOR.

ATTOE Ma s Patented Jan. 21, 1947 CORE GRINDER John A. Rosmait,Appleton, Wis., assignor to D. J. Murray Manufacturing 00., Wausau,Wis., a corporation of Wisconsin Application February 17, 1945, SerialNo. 578,440

2 Claims.

This invention relates generally to the art of grinding, and relatesmore specifically to improvements in the construction and operation ofmachines for facilitating the dressing and grinding of foundry cores orthe like.

The primary object of my present invention is to provide a new anduseful foundry core grinder which is simple in construction, flexible inits adaptations, and highly efficient in operation.

When manufacturing sand cores for foundry use, it frequently becomesdesirable to construct the cores in the form of mating sections whichare subsequently pasted or glued together to produce the completedcores. In order to produce perfect final core assemblages, the sectionsof each core must be dressed or ground so as to provide accurate planeand smooth surface coaction along the pasted areas, and to also obviatebroken bounding edges at these coasting surfaces. This grindingoperation has heretofore been rather slow and tedious, especially whenproducing large quantities of similar sectional cores; and in many caseslarge quantities of core sections either had to be scrapped, or the costof production was materially increased due to subsequent patchingnecessitated by broken edges or the like. The prior methods ofmanufacturing sectional sand cores have therefore proven quiteunsatisfactory and costly for various reasons, and it has heretoforebeen impossible to rapidly produce perfect composite cores having neatand highly finished appearance, at moderate cost.

It is therefore a more specific object of'the present invention toprovide an improved core grinding machine which may be utilized toovercome all of the above mentioned difficulties, and which is adaptedto quickly and effectively produce smooth and perfectly fiat surfaces ofcoaction upon the core-sections, without breaking or marring thebounding edges of these surfaces.

Another specific object of this invention is to provide an improved coregrinding assemblage of relatively compact and durable construction,which may be disposed in any convenient location, and safely operated bya novice to produce excellent results. i

A further specific object of my invention is to provide an improved coregrinding mechanism having large capacity, and adapted to be readilymanipulated and adjusted to dress sand cores or the like, having diversesizes and shapes.

Still another specific object of the invention is to provide a precisioncore grinderhaving enormous capacity, and which is operable withoutdanger of chattering to produce perfectly Smooth and clean surfaces ofcoaction, thereby effecting great savings in paste and labor necessaryfor production of the final cores.

An additional specific object of this invention is to provide anefiicient core dressing mechanism which may be constructed and operatedat moderate cost, and in which all parts are readily accessible forinspection while being thoroughly protected against sand and grit duringnormal use of the equipment.

These and other specific objects and advantages accruing from theinvention, will be more clearly apparent from the following detaileddescription.

A clear conception of the various features constituting my presentimprovement, and of the mode of constructing and of utilizing coregrinders embodying the invention, may be had by referring to thedrawings accompanying and forming a part of this specification whereinlike reference characters designate the same or similar parts in thedifierent views.

Fig. '1 is a part sectional side elevation of a' relatively small andportable core grinder built according to the invention, portions of theassemblage having been broken away to more clearly reveal normallyconcealed parts;

Fig. 2 is a top view of the upper portion of the core grinding unit ofFig. 1;

Fig. 3 is a part sectional side elevation of another core grinderembodying the invention but of larger capacity than that of Fig. 1, thismodified machine also having portions broken away in order to revealnormally concealed structure, and showing the core support revolvablefrom a slow speed motor directly through an endless belt drive;

Fig. 4 is an enlarged central vertical section through the anti-frictionbearing for mounting the core support upon the main column of themachine;

Fig. 5 is a transverse horizontal section through the machine of Fig. 1,taken along the line 5-5 and viewed in the direction of the arrows;

Fig. 6 is an enlarged central vertical section through the anti-frictionjournal and thrust bearing for the grinding wheel supporting shaft; and

Fig. 7 is a transverse horizontal section through a large capacitymachine such as shown in Fig. 3, the section being taken generally alongthe line l'l but above the annular apron associated with the revolvablecore support, and the core support being rotatable by an electric motorFigs. 1, 2, 4, 5 and 6, the relatively compact portable core grindershown therein comprisesin general a lower base 9 mounted on three wheelsIt, and having a sturdy upright column II firmly attached thereto atthelower extremity of the column; an upper bracket I2 verticallyslidably embracing the upper cylindrical portion of the column I I andcoacting with a spline I3 to positively prevent rotation of the bracketabout the column axis; a grinding wheel I l secured to the lowerextremity of a vertical shaft I5 disposed parallel to but remote fromthe column axis, and having its medial portion journalled for rotationin an anti-friction bearing assemblage I6 carried by the bracket I2,while its upper end is provided with a pulley H; a driving motor I8mounted upon the bracket I2 near the column II and being drivinglyconnected to the pulley I6 by a driving belt I9; a

' cap 23 resting upon the upper end of the column II and having anadjusting spindle 2| journalled for rotation therein, the upper end ofthe spindle being'provided with a hand wheel 22 for effectingrotationthereof while the lower elongated spindle portion 23 is screw threadedfor coaction with internal screw threads formed on thebracket I Z; .anda core supporting member 25 having a hub 25 rotatable about the lowerpart of the upper cylindrical portion of the column II and coacting withan annular shoulder 25 formed on the medial portion of this columnthrough an anti-friction thrust bearing assemblage .21, the member 24also being provided with an integral supporting plate or portion 23 forsupporting sand cores 29 or the like, and which is swingablehorizontally beneath the grinding wheel I4.

The main base 9 is preferably constructed in a. durable manner and inthe form of a three armed spider so that two of the transporting rollersI8 are disposed some distance away from and on opposite sides of thecolumn II, while the third roller I is located forwardly of and beyondthe axis of the shaft I and plate 28, as shown in Fig. 5. The base 9thus provides a substantial and firm portable support for the entirecore grinder; and in order to facilitate transportation of the machinefrom place to place, the base 9 may also be provided with a draft handle30 adapted to be held in upright position by means of a hook 3| securedto the column II, when the handle is not in use, as shown in Figs. 1 and5. The lower end of the the elongated spline I3 and shoulder 26 rigidlyand permanently associated therewith. The entire portion of the columnII above the fixed shoulder 25 is cylindrical and should be formed forsnug but sliding coaction with the bore of the bracket I2, so that thisbracketmay be adjusted vertically along the column II but will beprevented from revolving about the column axis by the spline I3. i

longitudinally of 4 The rotary grinding wheel I 4 is detachably securedto and suspended from the lower end of the shaft I5 by means of a nut32, and may be provided with a suitable guard 33 as indicated in Figs. 1and 2; and the combined guide and thrust bearing assemblage I B which iscarried by the forward portion of the bracket I2 and in which the shaftI5 is journalled, should be so constructed that the shaft I5 cannot tiltor shift its axis. This anti-friction bearing assemblage is illustratedin detail in Fig. 6, and comprises vertically spaced upper and lowerball bearings 34, respectively, of which the upper bearing 34 should belocated as near as possible to the pulley I! while the lower bearing 35is likewise disposed as near as possible to the grinding wheel l4. Theupper anti-friction bearing 34 is moreover formed and held in place by aretaining plate so as to assume upward thrust, while the loweranti-friction bearing is formed and likewise held in place so as to as-'sume downward thrust imposed upon the shaft I5, thereby insuringaccurate rotation of the' lower grinding face of the wheel [4 in anydesired horizontal plane as predetermined by adjustment of the bracketI2 along the column II. The shaft I5 and grinding wheel I4 are rotatableat relatively high speed, by power applied to the pulley I'I from'themotor I8 through one i or more endless V-belts I9, and the tension ofthese belts may be adjusted by shifting the motor I8 upon its carryingbracket I2 with the aidof tensioning screws 36 shown in Fig. 2.

The adjusting spindle supporting cap 29 rests upon the upper end of thecolumn II and may be firmly secured thereto in any suitable manner,.andthe manipulating hand wheel 22 which is secured to the upper extremityof the spindle 7 2I may be provided with a number of grip handles 31 asdepicted in Figs. 1 and 2. The threaded spindle portion 23 and thespline I3 should preferably be of considerable length, and since thespindle. H is journalled for free rotation in the fixed cap 20 but isprevented from shifting axially relative to this cap, rotation of thespindle with the aid of the hand wheel 22 will obviously cause thebracket I2 to move up or down dependent upon the direction of saidrotation and by virtue of the screw thread coaction of the spindleportion 23 with the internal bracket threads. This adjustment of thebracket I2 along the column. I I permits the grinding wheel I4 to bepositioned at any desired height above the core supporting plate 28; andthe bracket l2 may be locked or clamped to the column II in variouspositions of adjustment, by means of a locking screw element 38 coactingwith lugs 39 formed on the lower split portion of the main hub of thebracket I2, as clearly shown in Figs. 1 and 2. The wheel driving belt I9may also be normally concealed by a guard 40 as shown diagrammaticallyin Figs. 1 and 2, and above which the hand wheel 22 is located, but thisguard should be readily removable and is not essential, although it doesprotect the operator while manipulating the hand wheel.

Although the bracket I2 and grinding wheel I a may be thus adjustedvertically along the main column II, the core supporting assemblage 24is not shiftable. along this column, but is merely swingable about thecolumn axis as a center. As previously indicated, the core sup portingstructure comprises ahub 25 snugly, embracing but swingable about theupper cylindric'al portion of the column II, a core supporting plate 28formed integralwith the hub 25, and

provided with a lubricant injection fitting H for introducing abundantgrease to the space between the bearing zones. The upper end of the hub25 is closed and concealed by an annular cap 42 secured to the columnll, and the antifriction thrust bearing assemblage 21 consists of anannular ball bearing 43 which is thoroughly concealed and protected by acollar M secured to the bottom of the hub 25. This vertically elongatedbearing assemblage 23' while permitting the supporting plate 28 to beswung freely about the column i i in a horizontal plane, positivelyprevents the core support from moving out of this fixed plane.

The core supporting plate 28 of the relatively small core grinder ofFigs. 1 and 5, and which is swingable back and forth about the centralcolumn axis, may be circular or of any other desired shape, and isprovided with a series of anchoring grooves 55 of well knownconstruction to which the mounting frame 46 of the cores 29 may befirmly secured by means of bolts 41 or the like. The table or plate 28may also be provided with suitable gripping handles 48 for facilitatingswinging thereof, and it is to be noted that the centerline of the plate28 is swingable about the central axis of the column H on a radius whichis approximately equal to the distance from the column axis to thecenter of the grinding wheel supporting and driving shaft.

The somewhat modified larger capacity core grinders shown in 3 and 7,are quite similar to the smaller machine which has just been describedin detail, and function the same as the smaller grinder except that thecores 28 may be automatically swung about the column axis by powerapplied to the core support. Since the 1 column ii, bracket l2, grindingwheel l4 and the supporting, adjusting and driving elements associatedwith these various parts are the same in structure and function in bothmachines, their description will not be repeated. In the large capacitymachine, the lower extremity of the main column is rigidly secur d to arelatively heavy and sturdy base plate or base Ml of considerable area,and the core supporting assemblage 59 comprises an annular table orhorizontal plate 5i formed integral with a pivot hub 25 and adapted tobe constantly rotated about the column. axis by means of a motor driventapered friction roller '52 coacting with an annular lower surface 53formed on the table plate iii. The top of the plate 5! may be providedwith a series of radial core anchoring recesses or T-grooves .5 formedin radial stiffening ribs 54, so that an annular series of cores 29 maybe mounted upon the revolvable table, and the periphery of the plate 5|is provided with an annular apron 55 extending downwardly below thedriving roller 52. This driving roller 52 is mounted upon a shaft 56iournalled in a bracket 5'! secured to the base 49, and the inner end ofthe shaft 56 carries a pulley 5B which may either be driven directlyfrom a slow speed motor 59 through speed reducing endless belts fill, asshown in Fig. 3; or from a high s eed motor 5| through speed reductiongearing 62 and belts 68, as illustrated in Fig. 7. In either case, therevolution of the core supporting plate 5! by power, should be atrelatively slow speed in order to grind a perfectly smooth surface inone pass of the relatively soft sand core 29 beneath the abrasive wheel[4.

Since the operation and functioning of the two machines is substantiallythe same, it will suffice to describe the mode of use of only one of thecore grinders, so that the mode of utilizing the smaller core grinderwill be specifically described. During normal use of the core grindingmachine disclosed in Figs. 1, 2 and 5, the core 29 which is to bedressed should first be firmly applied to its frame 46 and this frameshould be firmly attached to the coresupporting plate 23 with the aid ofbolts 45. The plate 28 with the core 23 attached thereto will then befreely swingable about thecentral vertical axis of the column H in anobvious manner. The grinding wheel 14 should then be vertically adjustedby releasing the clamping screw 38 and manipulating the hand wheel 32 sothat the lower plane face of the wheel It will be at the proper distance from the upper plane face of the plate 28, in order to properlydress the upper surface of the core 29 when the core is swung into thezone of action of the wheel, and the clamping screw 38 should thereafterbe manipulated so as to lock the bracket l2 in the properly adjustedposition. The motor 58 may then be placed in operation to cause thegrinding wheel l4 to revolve rapidly about the central axis of itssupporting and driving shaft 5 5, after which the core supporting plate23 may be swung about the central axis of the column ii so as to. causethe core 29 to pass beneath the revolving grinding wheel.

\ Because ofthe fact that the sand cores 29 are relatively soft. ascompared to the grinding wheel it, it is onlynecessary to cause thewheel to travel once over the core, in order to insure the production ofsmooth core faces, but the wheel should be moved slowly in order toavoid breakage of the core edges adjoining the ground surfaces. In thismanner, the successive cores may be rapidly and effectivelydressed andsubsequently united along the smooth and plane dressed surfaces, withthe aid of paste or other adhesive in a well known manner, and byproperly manipulating the supporting plate 28, chipping and. breakage atthe edges of the dressed surfaces may be entirely eliminated, thusavoiding necessity of subsequent patching. i i

As previously indicated, the normal operation of the modified coregrinding machine shown in Figs. 3 and 7 is the same as that of themachine shown in Figs. 1, 2 and 5. but with the larger machine acontinuous annular series of cores 29 may be dressed automatically byutilizing a motor for driving the annular core supporting table plate5|. A series of similar cores 29' may obviously be secured to the plate5!, and this plate may subsequently be revolved about the central axisof the column I I by applying power to the friction roller 52, and aseach of the successive cores 2!! is passed beneath the revolving wheel Mwhich has previously been vertically adjusted to the proper height. theupper surfaces of the successive cores 29 will be neatly dressed andprovided with smooth and perfectly plane surfaces. Obviously thecapacity of the larger machine may be made considerably greater thanthat of the smaller portable machine, but in both cases the result willbe effective dressing of the cores so that they can. be subsequentlyunited along the dressed surfaces without difiiculty.

' From the foregoing detailed description it will be apparent that mypresent invention provides an improved core grinder which besides beingextremely simple, compact and durable in construction, is also highlyeificient in use. The elongated anti-friction bearings provided for thegrinding wheel driving shaft l and for the core supporting table orplate, will prevent misalinement of the wheel and table relative to eachother and will thus insure the provision of perfectly smooth and planesurfaces. The adjustment afforded for the bracket l2 and grinding wheelI obviously provides extreme flexibility in utilizing the machine todress cores of different sizes and shapes, and the smaller machine whilebeing of lesser capacity than the larger machine, is extremely compactand portable so that it can readily be moved into various localities. Inboth machines the grinding wheel l4 while being vertically adjustable,is effectively held against possible displacement relative to thecentral axis of the main column II, and in both machines the coresupporting table or plate is likewise effectively prevented frombecoming misalined with respect to the column axis while being freelyswingable about this axis. While the anti-friction bearings 34, 35, 43have been shown as ball bearings, it is to be understood that roller. orother types of anti-friction bearings may be employed in place of theseball bearings, in a manner well known in the art. The improved machinemay obviously be built and operated at moderate cost considering itseffectiveness, and the inven-- tion has proven highly successful andadvantageous in actual commercial use.

It should be understood that it is not desired to limit this inventionto the exact details of construction or to the precise mode of use,herein shown and described, for various modifications within the scopeof'the'appended claims may occur to persons skilled in the art.

I claim:

1. A core grinder comprising, a base, an upright column mounted uponsaid base and having an annular outwardly projecting shoulder and ashoulder, a core support swingable about said cylindrical column portionand coacting with the upper surface of said shoulder to prevent movementof the support along the column, a bracket having a hub slidablycooperable with said cylindrical column portion and being provided withan upright bearing remote from said hub and directly above the corecarrying portion of said support, an abrasive wheel journalled forrotation cylindrical portion projecting upwardly from said in saidbearing and having a grinding face revolvable beneath said bearingparallel to the plane of swinging of said core support, a motormounteddirectly upon said bracket hub, a rotary motion transmittingdrive connecting said motor and said wheel above said bearing and saidbracket, a spline interposed between said hub and said cylindricalcolumn portion for positively preventing swinging of said bracket aboutsaid column, a cap fixedly secured to the upper extremity of saidcolumn, a manually operable screw threaded adjusting spindle journalledin said cap and having its lower end cooperable with said bracket tomove the same along said column while its upper actuating end isdisposed above said drive, and means for locking said bracket to saidcolumn to prevent displacement of the bracket by said spindle.

2. A core grinder comprising, a base, an upright column mounted uponsaid base and having an annular outwardly projecting shoulder and acylindrical portion projecting upwardly from said shoulder, a coresupport swingable about said cylindrical column portion and coastingwith the upper surface of said shoulder to prevent movement of thesupport along the column, a motor also mounted upon said base beneathsaid support, a friction drive interposed between said motor and saidsupport for imparting swinging motion to the latter, a bracketv having ahub slidably coopera'ble with said cylindrical column portion and beingprovided with an upright bearing remote from said hub and directly abovethe core carrying portion of said support, an abrasive wheel journalledfor rotation in said bearing and having a grinding face revolvablebeneath said bearing parallel to the plane of swinging of said coresupport, another motor mounted directly upon said bracket hub, a rotarymotion transmitting drive connecting said last mentioned motor and saidwheel above said bearing and said bracket, a spline interposed betweensaid hub and said cylindrical column portion for positively preventingswinging of said bracket about said column,

a cap fixedly secured to the upper extremity of actuating end isdisposed above said drive, and

means for locking said bracket to said column to prevent displacement ofthe bracket by said spindle.

JOHN A. ROSMAIT.

